The Big 4 of Thrash Metal. My fucking go to genre of Metal. So anyway:

1. Slayer. Best Album: Hell Awaits. (Its slightly better than Reign in Blood)
2.Megadeth. Best Album: Rust in Peace (No contest really not that their older stuff is bad or the next)
3.Metallica. Best Album: ..And Jusitce for All (Its always Master of Puppers, Justice is the most Thrash of all the albums)
4. Anthrax. Best Album: Among the Living (Another no contest)

But I still enjoy other Thrash bands. Exodus, Testament, Overkill, Pantera. Testament in perticular man Chuck Billy's vocals is the true definition of a Thrash Metal vocalist.

SLAYER!!!!!
though after 'Reign In Blood' I'd go with 'Seasons in the Abyss' which used to bother me until Kerry King went on That Metal Show and said 'Abyss' was hands down their best record. Well, I don't know if he used the exact word "hands down" but he wanted to! :P

A thread about thrash metal and no one mentions M.O.D.? Sad!!!

That's because it doesn't have that. :P I never said it was a perfect record. XD I just think Abyss is better put together; the songs are more complex and filled out, and the record as a whole covers a larger scope of styles which to a lot of Slayer fans, like my brother, is a VERY VERY bad thing, but something I love.

Kill 'em All was always my close second for Metallica, but it wasn't thrash at the time.
Where's Death and Evil Chuck on the list!

While I like Anthrax the fact I saw them on tour with a band I like better doesn't help. (Public Enemy)

I'd rank it sorta like this
Megadeth
Metallica when they had Mustaine's material (aka the first three albums)
Testament
Anthrax with Joey Belladonna and their original vocalist
Metallica
Anthrax with John Bush

RWarehall mentioned Death, I wouldn't classify them quite as thrash metal to be honest but I will rank them as the best death metal/melodic death metal band ever.

+1 for and Justice for All appreciation. Though I always considered Justice to be more progressive than pure thrash than the other classic albums.

Metallica all the way for me. For some reason I never clicked with Megadeth or Anthrax, though I can appreciate them as bands.

It all sounds very painfull. Have you seen a doctor about it?

Uh in terms of thrash metal I'll take Testament, Destruction, Exodus and Anthrax. Slayer/Metallica are over hyped shite. They couldn't make a great album if they simply had to pull it out their arse hole. I like Some Megadeth but it gets a little tedious every now and again. Justice album was a glorified demo and an embarrassment to music. Shoddy production, poor songs and absolutely no quality control what so ever.

It took ten messages for a german band to be mentionned? Where's the love for Sodom and Kreator? :P

It can use better sounding drums and a louder bass.

Testament makes better ballads than Metallica though. So does extremely bombastic classical music like Gustav Holsts.

No, I meant the names... you know, Anthrax... like the disease... the joke... nevermind, I'll show myself out.

Testament does everything better than Metallica lol. As far as thrash band's go, those guys have some of the best talents. I mean Alex Skolnick would reduce Kirk and James into the ground within minutes with an acoustic guitar nevermind on electric.
The band nearly had to change their name because of that back in the early 2000's. What an odd time.

Loverboy!
Winger!
Warrant!